Drain water heat recovery exchangers, including coil drain water heat recovery exchangers, as described, for instance, in U.S. Pat. No. 7,322,404, include a central tube for receiving waste water and a pipe that is coiled around the central tube. The heat exchanger may also include other assembly components than just the coil. The tube receives warm waste water, for instance, from a shower, dishwasher or washing machine, and the coil pipe, or exchanger portion, receives cold water from a cold-water line. As the warm waste water enters the tube, the heat from the warm waste water is transferred to the tube, that is in turn transferred to the coil pipe, that then heats the cold water. As such, the cold water that exits the coil pipe is warmer than when it entered. The warmed cold water is transferred to the hot water tank, or, for instance, the cold-water line of a shower, where the work done to heat the cold water to the desired temperature is lessened due to the heat that was recovered from the warm waste water, transferred to the cold water entering the water supply system of the building.
The installation of a drain water heat recovery exchanger, as is known in the art, in a building, such as a household, proves to be a multi-step process that can be challenging and time consuming for the plumber or the installer, and costly for the building owner. Reference is now made to FIG. 1 herein, illustrating an exemplary method 10 of installing a drain water heat recovery exchanger as is known in the art.
First, a portion of the drain water pipe in the building may be cut out where the drain water heat recovery exchanger is to be installed at step 11. Then, the drain water heat recovery exchanger is connected in place of the cut out drain pipe at step 11, the tube of the drain water heat recovery exchanger aligned and fitted to the cut out drain pipe. Following this, as the ends of the coil pipe of the drain water heat recovery exchanger do not have fittings, connectors or joints (e.g. elbow joints; tee-joints) for connecting with the cold-water line pipe or the pipe leading to the cold-water line of a hot water consuming apparatus (e.g. shower) or the hot water tank, need to be added. The added fitting is compatible with the type of connecting pipe, such as a PEX (cross-linked polyethylene) pipe. Therefore, the plumber may solder on a joint at step 13 to one or both ends of the coil pipe, and is required to solder on to the ends of the coil pipe a fitting or a connector at step 14. However, the soldering of the fitting by the plumber is a dangerous process. There is a risk of fire due to the open flame involved. As a result, this step results leads to increased risk of property damage and injury. Moreover, the process of soldering is time consuming. Additionally, the purchase of a separate fitting to be soldered onto the drain water heat recovery exchanger results in additional installation cost, as the part is purchased separately.
Furthermore, after the fitting is soldered on, there is also a risk of leakage between the coil pipe and the soldered fitting. As a result, the plumber has to undertake an additional measure and verifies that the seal between the fitting and the coil pipe is watertight at step 15. Additionally, through usage of the drain water heat recovery exchanger over time, there is a risk that the connection between the fitting and the coil pipe fails, resulting in leaks. This increases the risk of water damage to the property.
After the adding of the fittings, the inlet of the coil pipe is connected to the cold-water line at step 16, and the coil pipe outlet is connected to the pipe leading to the cold-water line of a hot-water consuming apparatus (e.g. the shower, bath, faucet, etc.) or the hot water tank at step 17.
As a result, the soldering of the fitting required when installing the drain water heat recovery exchanger as is known in the art is dangerous for the building and the plumber and increases the time and cost of installation due to the requirement of having to purchase and install a separate fitting. Moreover, as the tradesman who installs the drain water heat recovery exchanger has to solder, the skillset of the tradesman is also greater, the installation more complex, the tradesman also needing to bring a greater assortment of tools onsite to complete the installation.